Generally, in a point-to-multipoint communication system including a donor unit and a plurality of remote units, a downlink information signal and a downlink control signal are transmitted from the donor unit to the plurality of remote units in a broadcasting manner. In this state, a unique ID is required for each remote unit for the purpose of communication between the donor unit and the remote unit. When the plurality of remote units simultaneously transmit control signals to the donor unit in a state in which the unique ID is not allocated to each remote unit, it is difficult to distinguish between the remote units that have transmitted the control signals, and collision between the control signals may occur.
However, according to a conventional art, in order to allocate a unique ID to each remote unit, a field worker should allocate, in a direct manual manner, an ID to a corresponding remote unit at an installation position of the remote unit. For example, there is an inconvenience in that the field worker should set port #1 of the donor unit and remote unit #1 one by one so that the port #1 of the donor unit and the remote unit #1 are connected to each other. In this process, there is a problem that a setting error occurs, and the like.